Pharmaceutical syringe piston

Patent metadata

Field	Value
Publication number	US-10258744-B2
Application number	US-201314758042-A
Country	US
Kind code	B2
Filing date	Apr 5, 2013
Priority date	Apr 5, 2013
Publication date	Apr 16, 2019
Grant date	Apr 16, 2019

Abstract

A pharmaceutical syringe piston having a longitudinal axis includes a body having a central face portion with a first outer circumference and maximum first diameter. A cylindrical sealing portion proximate the central face portion has first and second axial ends and a wall extending therebetween. The wall has a second outer circumference and a second diameter essentially constant along the longitudinal axis between the first and second axial ends of the cylindrical sealing portion and is larger than the maximum first diameter. An annular curved portion has a maximum outer diameter less than the second diameter and connects the first axial end of the cylindrical sealing portion to the first outer circumference. An inert film encloses the central face portion and at least a part of the annular curved portion and has an outer boundary between the first axial end of the cylindrical sealing portion and the first outer circumference.

First claim

What is claimed is:

1. A pharmaceutical syringe piston having a longitudinal axis and comprising:
a body having:
a central face portion having a first outer circumference oriented coaxially with respect to the longitudinal axis of the piston, and a maximum first diameter measured perpendicularly to the longitudinal axis of the piston,
a cylindrical sealing portion proximate the central face portion and oriented coaxially with respect to the longitudinal axis of the piston, the cylindrical sealing portion having a first axial end, a second axial end, and a wall extending therebetween, the wall having a second outer circumference and a second diameter measured perpendicularly to the longitudinal axis of the piston, the second diameter being essentially constant along the longitudinal axis between the first and second axial ends of the cylindrical sealing portion and being larger than the maximum first diameter of the central face portion, and
an annular curved portion connecting the first axial end of the cylindrical sealing portion to the first outer circumference of the central face portion, the entirety of the annular curved portion exhibiting an outwardly convex curve having a radius of curvature that extends into the body, the annular curved portion having an outer diameter less than the second diameter of the cylindrical sealing portion; and

an inert film enclosing the central face portion and at least a part of the annular curved portion and having an outer boundary disposed between the first axial end of the cylindrical sealing portion and the first outer circumference of the central face portion such that an outer surface of the inert film up to the outer boundary lies transverse to the longitudinal axis and no portion of the inert film extends along the body in a direction parallel to the longitudinal axis.

2. The pharmaceutical syringe piston of claim 1 , wherein the body further includes at least one radially protruding stabilizing rib proximate the second axial end of the cylindrical sealing portion and spaced apart therefrom along the longitudinal axis of the piston, the at least one stabilizing rib having a third outer circumference and a third diameter measured perpendicularly to the longitudinal axis of the piston.

3. The pharmaceutical syringe piston of claim 2 , wherein the body includes an annular recess disposed between the second axial end of the cylindrical sealing portion and the at least one stabilizing rib.

4. The pharmaceutical syringe piston of claim 3 , wherein the body includes the at least one radially protruding stabilizing rib including a plurality of stabilizing ribs spaced apart from the second axial end of the cylindrical sealing portion and from each other along the longitudinal axis of the piston, and a plurality of annular recesses, wherein each annular recess of the plurality of annular recesses is disposed between two of the stabilizing ribs.

5. The pharmaceutical syringe piston of claim 2 , wherein the third diameter is less than the second diameter.

6. The pharmaceutical syringe piston of claim 1 , wherein the body is formed from a resilient material.

7. The pharmaceutical syringe piston of claim 1 , wherein a center of the central face portion is spaced apart from the second outer circumference of the cylindrical sealing portion along the longitudinal axis of the piston.

8. The pharmaceutical syringe piston of claim 1 , wherein at least a portion of the body is coated with a lubricant.

9. The pharmaceutical syringe piston of claim 1 , wherein the inert film is formed of a fluorinated polymer material.

10. A pharmaceutical syringe for dispensing medicament, the syringe comprising:
a barrel configured to retain the medicament, the barrel having a longitudinal axis, an inner wall coaxial with respect to the longitudinal axis, a first axial opening, and an opposing second axial opening; and
a piston having a longitudinal axis and including:
a body having:
a central face portion having a first outer circumference oriented coaxially with respect to the longitudinal axis of the piston, and a maximum first diameter measured perpendicularly to the longitudinal axis of the piston,
a cylindrical sealing portion proximate the central face portion and oriented coaxially with respect to the longitudinal axis of the piston, the cylindrical sealing portion having a first axial end, a second axial end, and a wall extending therebetween, the wall having a second outer circumference and a second diameter measured perpendicularly to the longitudinal axis of the piston, the second diameter being essentially constant along the longitudinal axis of the piston between the first and second axial ends of the cylindrical sealing portion and being larger than the maximum first diameter of the central face portion and of a size sufficient to maintain the sealing portion in contact with the inner wall of the barrel, and
an annular curved portion connecting the first axial end of the cylindrical sealing portion to the first outer circumference of the central face portion, the entirety of the annular curved portion exhibiting an outwardly convex curve having a radius of curvature that extends into the body, the annular curved portion having an outer diameter less than the second diameter of the cylindrical sealing portion, and

an inert film enclosing the central face portion and at least a part of the annular curved portion and having an outer boundary disposed between the first axial end of the cylindrical sealing portion and the first outer circumference of the central face portion such that an outer surface of the inert film up to the outer boundary lies transverse to the longitudinal axis of the piston and no portion of the inert film extends along the piston body in a direction parallel to the longitudinal axis of the piston.

11. The pharmaceutical syringe of claim 10 , further comprising a longitudinally extending plunger shaft coupled to the second axial end of the piston body.

12. The pharmaceutical syringe of claim 11 , wherein the piston includes a receiving cavity formed from the second axial end of the piston body, the receiving cavity being configured to receive an end of the plunger shaft.

13. The pharmaceutical syringe of claim 11 , wherein the plunger shaft extends through the second axial opening of the barrel.

14. The pharmaceutical syringe of claim 10 , wherein the piston body further includes a plurality of radially protruding stabilizing ribs between the cylindrical sealing portion of the piston body and the second axial end of the piston body, each of the stabilizing ribs being longitudinally spaced apart from one another and the cylindrical sealing portion.

15. The pharmaceutical syringe of claim 14 , wherein each of the stabilizing ribs has an outer circumference, the outer circumference of each stabilizing rib being smaller than the second outer circumference of the cylindrical sealing portion of the piston body.

16. The pharmaceutical syringe of claim 14 , wherein the piston body further includes a plurality of annular recesses, wherein each annular recess is disposed between two of the stabilizing ribs.

17. The pharmaceutical syringe of claim 10 , wherein the face portion has a conical shape.

18. The pharmaceutical syringe of claim 10 , wherein at least a portion of the piston is coated with a lubricant.

19. The pharmaceutical syringe of claim 10 , wherein the inert film is formed of a fluorinated polymer material.

Assignees

• West Pharmaceutical Services Inc

Inventors

• Laubach Jeffrey M
• Brinkhues Jurgen
• Gruen Heike
• Worman Joel
• Zhao Xia
• Mattia Jason

Classifications

• A61M5/31513 Primary

  Piston constructions to improve sealing or sliding · CPC title

• A61M2205/0222

  Materials for reducing friction · CPC title